Portable rail cutting apparatus

ABSTRACT

A portable rail cutting apparatus is presented herein. The portable rail cutting apparatus comprises a housing encasing a motor, the motor configured to drive a rotary abrasive blade, a drive pulley coupled to the motor, a driven pulley coupled to the rotary abrasive blade, a loop drive belt engaged by the drive pulley at one end and engaging the driven pulley at another end, and an automatic belt tensioning mechanism. The automatic belt tensioning system comprises a spring and push rod assembly that applies a pre-set tension to the loop drive belt. The portable rail cutting apparatus may also comprise an adjustable protective guard member that partially surrounds the rotary abrasive blade and includes a detent mechanism configured to provide integral travel positions for the adjustable protective guard member.

This Application is a divisional of U.S. application No. 10/843,390filed May 12, 2004 now U.S. Pat. No. 7,059,947, the entire contents ofwhich is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a portable, rail cutting apparatus.

2. Description of the Related Art

During the laying of railroad tracks or the joining of railroad tracksections, rails may often need to be cut to specified lengths. Moreover,during railroad repairs, worn or damaged track sections may need to becut out and replaced with new rails. These rails or track sections aregenerally cut by a powered rail cutting saw.

Typically, rail cutting saws employ a rotating cutting blade, such as,an abrasive rotary disk, which is applied directly to the rail to effectthe desired cut. The rail cutting saw is powered by a motor, such as,for example, an internal combustion engine, which drives the cuttingblade via a drive assembly.

To provide support and stability, as well as effectively guide the sawover the intended cutting area, rail cutting saws may also be configuredto cooperate with a rail-mounted guide assembly. Generally, rail-mountedguide assemblies are arranged with a saw support portion and a railmount portion. On the saw support portion, the assembly attaches to thebody of the rail saw proximately along the center line between the drivepulley and the driven pulley. On the rail mount portion of the guideassembly, the assembly either clamps, joins, or otherwise secures therail saw to the rails.

The drive assembly that drives the cutting blade, typically comprises aloop drive belt arrangement having one end of the belt coupled to adrive pulley, engaged by an output shaft of the motor. The other end ofthe belt is coupled to a driven pulley that engages the cutting blade.Generally, the driven pulley is coupled to the motor housing via asliding support arm arrangement. The sliding support arm arrangementoverlaps the fixed motor housing and, when the portions are not fastenedtogether, the sliding portion is arranged to laterally slide relative tothe fixed motor housing.

The sliding portion of the support arm arrangement supports the drivenpulley while the fixed portion is the motor housing. The two portionsare kept in place and prevented from sliding by fasteners that securethe two portions to each other. Upon loosening or removing thefasteners, the sliding portion is capable of laterally sliding intowards the motor housing or sliding out towards the driven pulley.

After a period of normal use, the loop drive belt may become loose. Assuch, rail saws may also be equipped with a manual belt tensioningsystem that enables the user to manually adjust the tension on the loopdrive belt. Some belt tensioning systems comprise a tensioning screwthat is positioned close to the center line between the drive and drivenpulleys. In this belt tensioning system, the sliding support armfasteners are first loosened or removed so that, as the tensioning screwis manually tightened, the sliding support arm arrangement slides orlaterally extends out to increase the lateral distance between the drivepulley and the driven pulley. The increased distance serves to tightenthe loop drive belt.

Other belt tensioning systems comprise a cam adjustment device, in whicha cam structure and a post structure are positioned on the slidingsupport arm arrangement. With the sliding support arm fasteners loosenedor removed, the cam portion is rotated to impart a tensioning force onthe post structure that serves to slide or laterally extend the slidingsupport arm arrangement to increase the lateral distance between thedrive pulley and the driven pulley, and thus, tighten the loop drivebelt.

Rail cutting saws may also be equipped with an adjustable protectiveblade guard to reduce the risk of injury from flying debris and/or blademalfunction. In some instances, the blade guard may be kept in place byfasteners that require the use of tools to effect guard positionaladjustments. That is, to adjust the guard position, the fasteners aremanually loosened with the tool, the guard is rotated or pivoted intoits new position, and then the fasteners are manually retightened withthe tool to secure the guard in its new position.

In other instances, the blade guard may held in place by frictionsurfaces, thereby avoiding the use of tools to adjust the guardposition. In this tool-less configuration, the friction surfaces aredisposed at or near the pivot center of the blade guard and the bladeguard position is adjusted by pushing or pulling a guard handle securedto the circumference of the blade guard. Attaching the handle to thecircumference of the blade guard provides the mechanical advantage offacilitating the necessary torque to overcome the holding strength ofthe friction surfaces.

SUMMARY OF THE INVENTION

As noted above, some rail saws may be equipped with a manual belttensioning system that enables the user to manually adjust the tensionon the loop drive belt. However, such belt tensioning systems rely onoperator intuition to estimate the required adjustments. Suchestimations often lead to under-tightening, which results in beltslippage, or over-tightening, which results in premature wear.

For at least these reasons, the principles of the present invention, asembodied and broadly described herein, provide a portable rail cuttingapparatus having an automatic belt tensioning system that applies apre-set tension to the loop drive belt and, thus, avoids reliance onoperator estimation. In one embodiment, the portable rail cuttingapparatus comprises a housing encasing a motor, the motor configured todrive a rotary abrasive blade, a drive pulley coupled to the motor, adriven pulley coupled to the rotary abrasive blade, a loop drive beltengaged by the drive pulley at one end and engaging the driven pulley atanother end, and an automatic belt tensioning mechanism. The automaticbelt tensioning system comprises a spring and push rod assembly thatapplies a pre-set tension to the loop drive belt.

As noted above, some rail saws may be equipped with tool-less adjustableprotected blade guards that employ friction surfaces positioned near thepivot center of the guard. However, because the friction surfaces arelocated near the pivot center, there is a greater likelihood of bladeguard malfunction during cutting wheel failures.

Accordingly, the present invention further provides a portable railcutting apparatus having an adjustable protective blade guard with atool-less detent mechanism that locks the blade guard in place andavoids malfunctions caused by cutting wheel failures. In one embodiment,the portable rail cutting apparatus, comprises a housing encasing amotor, the motor configured to drive a rotary abrasive blade, a drivepulley coupled to the motor, a driven pulley coupled to the rotaryabrasive blade, and an adjustable protective guard member that partiallysurrounds the rotary abrasive blade and includes a detent mechanismconfigured to provide integral travel positions for the adjustableprotective guard member.

The detent mechanism is disposed proximate to a periphery of theadjustable protective guard member and includes a slot having a seriesof apertures defining the integral travel positions and aspring-actuated knob piston. The spring-actuated knob piston engages oneof the apertures to lock the adjustable protective guard member into oneof the integral travel positions and depressing the spring-actuated knobpiston disengages the spring-actuated knob piston enabling theadjustment of the protective guard member.

BRIEF DESCRIPTION OF DRAWINGS

The present invention will be described with reference to drawings, inwhich:

FIG. 1A is a side elevation view with cut-out portions of a portablerail cutting apparatus, in accordance with the present invention;

FIG. 1B is a front view of the portable rail cutting apparatus;

FIG. 1C depicts portions of an engaged protective guard member detentsystem, in accordance with the present invention;

FIG. 1D depicts a disengaged protective guard member detent mechanism;

FIG. 2A is a side elevation view of an automatic belt tensioning system,in accordance with the present invention; and

FIG. 2B is a bottom view of the automatic belt tensioning system.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1A depicts a side elevation view of a portable rail cuttingapparatus 10, in accordance with the present invention. Rail cuttingapparatus 10 comprises a motor 20, a drive assembly 30, a cutting blade40, and an automatic belt tensioning system 50. Motor 20 comprises aninternal combustion-type engine that is encased within a motor housing20A. It will be appreciated that motor 20 may be also comprise anelectric induction motor or any motor suitable for such purposes. Motor20 includes an output shaft 20B, which is coupled to, and configured todrive, a drive pulley 30A.

In the embodiments described below, cutting blade 40 comprises a rotaryabrasive disc or blade. It will be appreciated, however, that anysuitable disc blade capable of cutting metal may be used. The rotaryabrasive blade 40 is engaged by, and coupled to, a driven pulley 30B.The rotary abrasive blade 40 is partially covered by an adjustableprotective guard member 40A. The rotary abrasive blade 40 and drivenpulley 30B are supported by one end of a spindle mount arm 30D. Asbetter illustrated in FIG. 2A, the other end of spindle mount arm 30Dincludes a slotted portion 30I that is securely attached to the body ofmotor housing 20A via fasteners 20D, such as bar clamp nuts or the like.Fasteners 20D are threaded onto threaded posts 20C, which are fixedlyattached to the body of motor housing 20A.

To increase the lateral distance between drive pulley 30A and drivenpulley 30B (to maintain tension on the drive belt, as discussed ingreater detail below), spindle mount arm 30D is constructed with thecapability of being able to travel a pre-specified distance along alateral direction. Specifically, slotted portion 30I of spindle mountarm 30D is configured so that the slot spans a length that is greaterthan the length spanned by posts 20C, enabling spindle mount arm 30D tolaterally slide out for a distance that is equivalent to the differencebetween the slot and post 20C lengths.

Spindle mount arm 30D also includes an attachment portal 30H, positionedproximately along the center line between drive pulley 30A and drivenpulley 30B, in order to enable the coupling of a rail-mounted guideassembly to rail cutting apparatus 10.

Drive assembly 30 comprises drive pulley 30A, driven pulley 30B, and aloop drive belt 30C. Lop drive belt 30C may comprise a flexible band,chain, or any other belt suitable for such purposes. Loop drive belt 30Cpartially wraps around drive pulley 30A and driven pulley 30B. Duringoperations, drive pulley 30A engages loop drive belt 30C which, in turn,engages driven pulley 30B to rotate rotary abrasive blade 40.

Belt tensioning system 50 is configured to apply a preset tension toloop drive belt 30C and to automatically impart the appropriate tensionupon adjustment. In particular, belt tensioning system 50 comprises aspring 50A, push rod 50B, and tension nut 50C assembly. Becauseattachment portal 30H is generally positioned along the center linebetween drive pulley 30A and driven pulley 30B, spring 50A, push rod50B, and tension nut 50C assembly are disposed at an off-center positionbetween said drive pulley 30A and said driven pulley 30B.

Push rod 50B includes a threaded portion, in which tension nut 50C isthreaded thereon. Push rod 50B is inserted through guiding holes ofshoulder mounts 30E, 30F of spindle arm 30D as well as spring 50A.Spring 50A is interposed between tension nut 50C and shoulder mount 30E.

In one embodiment, tension nut 50C is threaded and adjusted duringassembly so that it aligns with a tension line marker 30G, as depictedin FIG. 2B. Tension line marker 30G is provided on spindle mount arm 30D(e.g., on the underside of 30D in FIG. 2B) to identify a desirableposition of tension nut 50C that corresponds to the desired pre-settension. So, adjusting tension nut 50C to line marker 3OF compressesspring 50A, which bears a pre-set tension force on shoulder mount 30E ofspindle arm 30D. Commensurately, push rod 50B bears the pre-set tensionforce on a housing mount portion 20B of motor housing 20A.

The pre-set tension force on housing mount portion 20B, imparted by pushrod 50B, laterally extends spindle mount arm 30D out from motor housing20A. This spindle mount arm 30D extension translates the pre-set tensionto loop drive belt 30C. In other words, the pre-set tension forcelaterally extends spindle mount arm 30D which, as indicated above,supports driven pulley 30B that is coupled to drive belt 30C. Thisresults in achieving a desired lateral distance between drive pulley 30Aand driven pulley 30B that corresponds to the application of the pre-settension force on drive belt 30C. In this manner, belt tensioning system50 applies the preset tension force to loop drive belt 30C to ensurethat drive belt 30C achieves the proper tension.

The pre-set tension force on housing mount portion 20B also defines aninitial locking position for spindle arm 30D during assembly. That is,upon aligning tension nut 50C with tension line marker 30G duringassembly, spindle arm 30D is locked into position by securing slottedportion 30I of spindle mount arm 30D to the body of motor housing 20A bytightening fasteners 20D onto threaded posts 20C.

As discussed above, loop drive belt 30C may become loose after normaluse. By virtue of its configuration, automatic belt tensioning system 50facilitates re-tensioning adjustments by simply loosening andretightening fasteners 20D. Specifically, by loosening fasteners 20D,spindle mount arm 30D is released from the initial locked position sothat the pre-set tension force of belt tensioning system 50automatically extends spindle arm 30D further out from the body of motorhousing 20A in a lateral direction. Accordingly, slotted portion 30Itravels to a new lateral position (i.e., to the right in FIG. 2A). Thisfurther extension translates the pre-set tension to loop drive belt 30C,tightening drive belt 30C to eliminate any slack in loop drive belt 30Cand to, once again, ensure that drive belt 30C achieves the propertension. Retightening fasteners 20D onto threaded posts 20C after there-tensioning adjustment, locks in slotted portion 30I to the newlateral position, thereby locking in the adjustment.

Thus, re-tensioning adjustments of the present invention do not rely onoperator intuition to estimate re-tensioning adjustments, but areautomatic. This results in the reduction of drive belt under-tightening,which may lead to belt slippage, and drive belt over-tightening, whichmay lead to in premature wear.

As illustrated in FIG. 1A and noted above, rotary abrasive blade 40 ispartially surrounded by an adjustable protective guard member 40A. Guardmember 40A includes a detent mechanism 40B that facilitates thetool-less positional adjustment of guard member 40A. Detent mechanism40B is proximately positioned along the periphery of guard member 40Aand comprises a guide slot 40C configured with a series of apertures40N, spaced at predetermined locations, and a spring-actuated knobpiston 40D. Apertures 40N are configured with a larger diameter than thewidth of slot 40C.

The combination of slot 40C and apertures 40N provide integral travelpositions to which guard member 40A can be adjusted. In other words,slot 40C and apertures 40N are constructed and operative to limit thepositional adjustment range of guard member 40A. The span of slot 40C,which corresponds to the positional adjustment range of guard member40A, is configured so that guard member 40A cannot be adjusted to aposition that exposes the operator.

As better illustrated in FIG. 1C, which depicts detent mechanism 40Bengaged, spring-actuated knob piston 40D comprises a piston 40E a spring40J. Piston 40E contains a head portion 40F having a larger diameterthan a piston rod portion 40G. Detent mechanism 40B is configured sothat, when engaged, head portion 40H fits within one of the apertures40N, but not within guide slot 40C. This results in effectively lockingin protective guard member 40A into the travel position that correspondsto the engaged aperture.

When disengaged (as illustrated by FIG. 1D), detent mechanism 40Bextends piston rod portion 40G, so that portion 40G fits within guideslot 40C and protective guard member 40A can be rotated to freely travelalong the extent of slot 40C.

Piston rod 40G is inserted through a guide hole (not shown) of a pistonmount 40I. Piston rod 40G is attached to a knob portion 40H. Interposedbetween knob portion 40H and piston mount 40I is spring 40J. When detentmechanism 40B is engaged, spring 40J biases knob portion 40H outward sothat piston head portion 40H remains securely disposed within one of theapertures 40N and protective guard member 40A remains locked into thetravel position that corresponds to the engaged aperture.

To adjust protective guard member 40A to one of the integral travelpositions defined by apertures 40N, detent mechanism 40B is disengagedby sufficiently pressing knob portion 40H to overcome the biasing forceof spring 40J and extend piston head portion 40H beyond the plane ofguide slot 40C. As illustrated in FIG. 1D, in so doing, piston rodportion 40G comes into communication with the plane of guide slot 40C.As noted above, rod portion 40G fits within guide slot 40C, therebyenabling protective guard member 40A to be freely rotated along theextent of guide slot 40C.

When a desired guard member 40A position is reached, knob portion 40H isreleased so that piston head portion 40H securely settles into thenearest aperture 40N and protective guard member 40A is locked intoposition.

In this manner, detent mechanism 40B enables the tool-less positionaladjustments of protective blade guard member 40A. It will be appreciatedthat because detent mechanism 40B is situated close to the circumferenceof guard member 40A, it manifests a greater mechanical advantage thanconventional tool-less configurations that have friction surfaceslocated near the guard pivot center. As such, it is also more resistantto blade guard movement during cutting blade failures.

While specific embodiments of the invention have been described above,it will be appreciated that the invention may be practiced otherwisethan as described. As such, the description is not intended to limit theinvention. The configuration, operation, and behavior of the presentinvention has been described with the understanding that modificationsand variations of the embodiments are possible, given the level ofdetail present herein. Thus, the preceding detailed description is notmeant or intended to, in any way, limit the invention—rather the scopeof the invention is defined by the appended claims.

1. A portable rail cutting apparatus, comprising: a housing encasing amotor, said motor configured to drive a rotary abrasive blade; a drivepulley coupled to said motor; a driven pulley coupled to said rotaryabrasive blade; a loop drive belt engaged by said drive pulley and bysaid driven pulley; and an adjustable protective guard member, partiallysurrounding said rotary abrasive blade, that includes a detent mechanismconfigured to provide integral travel positions for said adjustableprotective guard member, said detent mechanism containing a series offirst locking elements defining said integral travel positions and aspring-actuated second lock structure, wherein said detent mechanism isdisposed proximate to a periphery of said adjustable protective guardmember, and wherein said spring-actuated second lock structure ismovable into a locking position wherein it engages one of said firstlocking elements to lock said adjustable protective guard member intoone of said integral travel positions and movable into a releasingposition wherein it is enabling the adjustment of said protective guardmember.
 2. The rail cutting apparatus of claim 1, wherein said firstlocking elements comprise a plurality of apertures disposed along aslot, said apertures being configured with a larger diameter than thewidth of said slot.
 3. The rail cutting apparatus of claim 2, whereinsaid second lock structure comprises a spring-actuated knob piston, saidspring-actuated knob piston comprising a knob portion, a piston, and aspring, said piston having a head portion and a piston rod portion inwhich said piston head portion has a larger diameter than said pistonrod portion.
 4. The rail cutting apparatus of claim 3, wherein saidpiston head portion fits with said apertures and said piston rod portionfits within said slot.
 5. The rail cutting apparatus of claim 3, whereinsaid detent mechanism is engaged when said spring biases said knobportion so that piston head portion remains securely disposed within oneof said apertures and said protective guard member remains locked into aposition that corresponds to said engaged aperture.
 6. The rail cuttingapparatus of claim 3, wherein said detent mechanism is disengaged whenpressure is applied to said knob portion sufficient to overcome bias ofsaid spring to extend said piston rod portion into said slot, therebyenabling said guard member to move along said slot.
 7. The rail cuttingapparatus of claim 6, wherein said protective guard member is adjustedby disengaging said detent mechanism, moving said guard member to adesired position, and removing pressure from said knob portion to allowsaid piston head portion to fit within a nearest one of said aperturesthat corresponds to the desired position.
 8. The rail cutting apparatusof claim 1, wherein said slot spans a distance that limits a range thatsaid adjustable protective guard member is capable of traveling in orderto prevent exposure to an operator.
 9. A hand-operated rail cuttingapparatus, comprising: a housing encasing a motor, said motor configuredto drive a rotary abrasive blade; a drive pulley coupled to said motor;a driven pulley coupled to said rotary abrasive blade; a loop drive beltengaged by said drive pulley at one end and engaging said driven pulleyat another end; an automatic belt tensioning mechanism containing aspring and push rod assembly to apply a pre-set tension to said loopdrive belt, said spring and push rod assembly disposed at a locationoff-center between said drive pulley and said driven pulley; anadjustable protective guard member partially surrounding said rotaryabrasive blade, said adjustable protective guard member including adetent mechanism configured to provide integral travel positions forsaid adjustable protective guard member, said detent mechanismcontaining a slot, disposed proximate to a periphery of said adjustableprotective guard member, having a series of apertures defining saidintegral travel positions and a spring-actuated knob piston, whereinsaid spring-actuated knob piston engages one of said apertures to locksaid adjustable protective guard member into one of said integral travelpositions and depressing said spring-actuated knob piston disengagessaid spring-actuated knob piston enabling the adjustment of saidprotective guard member.